How should refractory materials for glass furnaces be selected?
Publish Time:
2023-07-11
For large float lines, the structure of a glass furnace typically consists of an L-shaped hanging wall (usually using silica bricks), a melting section (the area in direct contact with the molten glass uses electrofused bricks, while the top uses silica or electrofused bricks), a bottleneck (usually using silica bricks), a cooling section including a forehearth (areas in direct contact with the molten glass usually use alumina materials, while areas not in direct contact use silica or alumina bricks), an annealing furnace, and regenerators (made of high-alumina bricks, clay bricks, and directly bonded magnesia-chrome bricks).
1. Furnace Crown
The furnace crown (including the crown angles) of the melting and cooling sections of a glass melting furnace operates at 1600℃. Refractory materials used in these areas must withstand high temperatures and loads while also resisting erosion from alkali vapor and batch materials. Therefore, refractory materials used for the crown must have high refractoriness, high load softening temperature, and good creep resistance. They should also have low thermal conductivity, not contaminate the molten glass at high temperatures, have relatively low bulk density, and good high-temperature strength.
High-performance, high-purity silica bricks possess these characteristics:
a. High load temperature, approaching its refractoriness;
b. Good high-temperature stability and high compressive strength;
c. Since the main component is SiO2, with a content >96%, which is the same as the main elemental composition of glass, erosion at high temperatures will essentially not contaminate the molten glass;
d. Inexpensive.
Therefore, high-purity silica bricks are the ideal product for various glass furnace crowns in various glass production processes.
Chemical erosion caused by high-temperature chemical reactions between batch materials and alkali vapor and refractory materials, as well as crystallographic transformations and changes in structural density due to phase migration and temperature, are the main causes of crown brick damage.